/mä-jə-lər ek-spə-nen(t)-shē-ā-shən/
raising an integer to the power of another integer, modulo some integer. For integers a, n, and m, am mod n.
For example, 53 mod 100 = 25.
Modular exponentiation can be done fairly quickly with a sequence of bit shifts and adds, and special purpose chips have been designed.
See also discrete logarithm problem.